An aim of integrated population modelling is to provide a single, coherent analysis of a range of data sets collected from diﬀerent surveys, all relating to the same species. In the area of fisheries, the idea was presented in Fournier and Archibald (1982), and there have been several developments in that area since then, as described in the review by Maunder and Punt (2013). In fisheries research the approach is termed integrated analysis. The work we describe in this chapter originates from a parallel development in Besbeas et al. (2002), and we shall mainly focus on combining demographic data with count/census data. However, information on productivity, for example, could also be included and for illustration we now consider two possibilities for modelling productivity.